1. Field of the Invention
This invention relates to a method for modifying a stent in an implanted site, and more particularly to a method of altering any stent in an implanted site by subjecting the stent to pulses of laser energy from external means thereby altering their physical structure without substantially altering or damaging tissue surrounding the implanted site.
2. Description of the Related Art
The use of lasers to break down a calculus, stone or calcified tissue for removal from within the human body is disclosed in Watson et al., U.S. Pat. No. 4,887,600. Watson et al. refer to the delivery of a laser beam via an optical fiber to break down these materials for removal from within the human body. A ureterscope with a dye laser is inserted to reach the site of a stone, such that the distal face of a fiber thereof contacts the stone. After irrigation of the site so that the stone is surrounded by liquid, pulses of laser energy at a wavelength between 450 and 550 nm are delivered at not exceeding about 200 millijoules per pulse at a repetition rate of between 10 and 50 Hertz. The stone breaks down into a combination of about 10% vapor, the remainder being easily removed sand-like particles. An excimer laser is noted as being less desirable. An excimer laser will produce a breakdown product of approximately 90% vapor. Watson discloses only breakdown of urinary calculi, gallstones, arterial plaque and calcified tissue.
Artificially induced degradation of stents has not previously been disclosed. A need exists to provide a method of ablating biodegradable stents. Further, a need exists for a method of vaporizing or accelerating the degradation of biodegradable stents through extracorporeal means. A need also exists for a method of altering the physical structure of any implanted stent without substantially altering or damaging the tissue surrounding it.
The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is "prior art" with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. .sctn.1.56 (a) exists.